Advanced Custom Field Pro < 5.9.1 - Reflected Cross-Site Scripting (XSS)

published 2021-04-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-11155

cvss: 6.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.4%; EPSS 1.4% chance of exploitation in 30 days, percentile 72%
public exploits: 0; none known

The Advanced Custom Fields Pro WordPress plugin before 5.9.1 did not properly escape the generated update URL when outputting it in an attribute, leading to a reflected Cross-Site Scripting issue in the update settings page.

Patch / fix

fixed in 1

advancedcustomfields advanced_custom_fields 5.9.1

Exploit prediction

1.39% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

wpscan.com https://wpscan.com/vulnerability/d1e9c995-37bd-4952-b88e-945e02e3c83f referenced PoC, tagged "exploit" by a source, unverified
github.com https://github.com/jdordonezn/Reflected-XSS-in-WordPress-for-ACF-PRO-before-5.9.1-plugin/issues/1 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

Unknown Advanced Custom Fields Pro

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

Technology feeds

WordPress rss critical rss

References

wpscan.com /vulnerability/d1e9c995-37bd-4952-b88e-945e02e3c83f
exploit, third-party-advisory
github.com /jdordonezn/Reflected-XSS-in-WordPress-for-ACF-PRO-before-5.9.1-plugin/issues/1
exploit, third-party-advisory
advancedcustomfields.com /blog/acf-5-9-1-release/
release-notes, vendor-advisory

Sources

CVE List CVE-2021-24241
NVD CVE-2021-24241

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary